The metered Porrofinders used CDS cells in the meters, and (IIRC) mercury cell batteries. By now, they are also quite old. So if you find one, the metering may or may not still be functioning, and if they are functioning, you need to implement one of the battery replacement work-arounds.
And they are both relatively dim and quite bulky (as you will know from the one you have).
Personally, I would prefer one of the metering chimney finders, even if they share the same meter cell/battery cell concerns.